Rind color is an economically important agronomic trait in eggplant that impacts consumer preferences. In this study, bulked segregant analysis and competitive allele-specific PCR were employed to identify the candidate gene for eggplant rind color through constructing a 2794 F2 population generated from a cross between “BL01” (green pericarp) and “B1” (white pericarp). Genetic analysis of rind color revealed that a single dominant gene controls green color of eggplant peel. Pigment content measurement and cytological observations demonstrated that chlorophyll content and chloroplast number in BL01 were higher than in B1. A candidate gene (EGP19168.1) was fine-mapped to a 20.36 Kb interval on chromosome 8, which was predicted to encode the two-component response regulator-like protein Arabidopsis pseudo-response regulator2 (APRR2). Subsequently, allelic sequence analysis revealed that a SNP deletion (ACT→AT) in white-skinned eggplant led to a premature termination codon. Genotypic validation of 113 breeding lines using the Indel marker closely linked to SmAPRR2 could predict the skin color (green/white) trait with an accuracy of 92.9%. This study will be valuable for molecular marker-assisted selection in eggplant breeding and provides theoretical foundation for analyzing the formation mechanism of eggplant peel color.

Rind color is an economically important agronomic trait in eggplant that impacts consumer preferences. However, the gene(s) regulating eggplant rind color have not been characterized. In this study, bulked segregant analysis (BSA) and kompetitive allele-specific PCR (KASP) were employed to identify a candidate gene for eggplant rind color through constructing an F2 population generated from a cross between 'BL01' (green pericarp) and 'B1' (white pericarp). Genetic analysis of rind color revealed that a single dominant gene controls green color of eggplant peel. Pigment content measurement and cytological observations demonstrated that chlorophyll and carotenoid content and the number of chloroplasts and thylakoids in BL01 were higher than in B1. Using a BSA-seq method and a recombinant mapping strategy in F2 plants, a candidate gene (EGP19168.1) was fine-mapped to a 20.36 Kb interval on chromosome 8. The gene is predicted to encode the two-component response regulator-like protein Arabidopsis pseudo-response regulator2 (APRR2). Subsequently, allelic sequence analysis revealed that a single-base deletion in white-skinned eggplant led to a premature termination codon. A credible molecular marker closely linked to the candidate gene was developed to genotype 45 diverse eggplant germplasms, which could predict the trait of rind color (green and white) with a 91.1% accuracy rate. This study will be valuable for molecular marker-assisted selection in eggplant breeding and provides theoretical foundation for analyzing the formation mechanism of eggplant peel color.